In order to obtain an adequate quality of the coke coking coal can be compacted in specially provided molds by means of power hammers moving up and down. In the compressing devices of German open application 29 14 918 the individual hammers are lifted by cam disks mounted on a throughgoing shaft and actuated by a driving motor. By rotation of both cam disks, these are caused to press in a cam-like protruding area of their circumferences against the web, provided with a friction lining, of the corresponding hammer and lift the hammer due to the effect of the friction force. Upon further rotation the disk cams return to the recessed area of their circumferences and release the power hammer so that it falls and compresses the coking coal.
The cam disks of each side of the power-hammer device have a common shaft per hammer carriage, driven by a gear. On their part, the gears of both shafts are driven by an electromotor through an intermediate gear and a drive unit. The bearings of the shafts are bolted in the frame structure and lined underneath with a stack of shim plates. In order to adjust the cam-disk shafts, the bearings must be dismounted from the frame structure and the shaft can be lifted together with the cam disks and bearings with the purpose of compensating the thickness of the shimming with respect to the degree of wear of the friction lining and to insure the required friction force for lifting the hammer.
The adjustment of the cam-disk shafts is requires to a large expense in effort and time, although it is sufficient, as a rule, to adjust only one of the two shafts. An adequate device, for instance a hoist, is required to lift the cam-disk shaft.
In addition, for each adjustment of the shaft the intermeshing between the cam-disk shaft-pinion and the intermediate gear has to be readjusted. If this operation is not performed scrupulously, damage of the gears through stressing and increased wear is unavoidable. The difficulties are increased by the fact that the required correction of the thickness of the shim package can not be predetermined or foreseen. As a result, in certain cases the adjustment must be repeated, for instance when too many or too thick plates were removed and the bearings are then subjected to unacceptable stress and heat following an increased contact pressure.
In order to keep down-time as low as possible in practice, the cam-disks shaft is adjusted as a rule only then when one or more power-hammer rods are no longer lifted.
In the intermediate stage a slip occurs between the web of the hammer rod and the cam of the disks, due to reduced friction. As a result of the diminished lifting of the power hammer the compression of the coking coal and of the coal cakes to be introduced into the oven for coking are reduced.
In case the operator notices too late, or not at all, that the rods of the hammer have failed to go up, considerable damage can be produced. In this case the unlifted hammers rods remain in the coal cake and are rammed while the carriages are moved forwards by means of a hydraulic cylinder. This can lead to the bending of the power-hammer rods stuck in the solidified coal cake. As a rule, in this case the replacement of the power-hammer rods is unavoidable.
Since the two traversing cam-disks shaft are actuated by a common drive, the cam disks mounted on them can be aligned only together. As a result, each alignment is carried out based on the power-hammer rod whose web and lining thickness are in the worst condition. Only by proceeding in this manner one can be sure that the power-hammer rods are indeed being lifted, since the initial stressing force was based on the most unfavorable situation. However it is also disadvantageous that the remaining cam disks are pressed against the lining with a contact pressure higher than the one needed. The result is a comparatively higher wear of the friction lining.